ANT Forum

Hello,

I'm implementing a pair of MCUs where one is operating a ANT+/BLE radio stack using the S332 soft device. Whilst TWIS is disabled, we're getting great performance, approximately 98% EVENT_RX success upon reading a ANT+ power profile channel.

We use the TWIS interface on this device in order to communicate with the other MCU. As soon as the TWIS interface is enabled and begins processing messages (in either synchronous or asynchronous mode, and independent of bitrate) the EVENT_RX rate plummets and we're left with a seriously degraded radio stack - BLE also sees large failure rates. Roughly 40% of all messages are EVENT_RX_FAIL leading to many instances of dropped power messages.

Is this expected behaviour, or is there any workaround?      

I would expect TWI operations to need to complete and thus cannot be interrupted by wireless activity required by BLE and ANT. My suggestion would be to try and run your TWI calls only after ANT & BLE have indicated that they have completed activity (EVENT_RX, EVENT_TX, etc).

Really the issue boils down to there is only one CPU, and wireless activity events are very timing sensitive.      

The problem was that I was using pins on the MCU marked on the datasheet as unsuitable for high speed signaling alongside radio use. Moral of the story, always read the datasheet. Dremel on the PCB, but of a wrapping wire nest, and we are fixed... Nearly 100% success rate reported on the RX.